Fuel confusion S8 D2 FL...

[Rightthen]

Looking for things I may have missed concerning fueling issue before i start investigating the rats nest in the tank. I'll try to get as much relevant info as I can....

My S8 D2 FL has been suffering intermittent fuel starvation for a while. Finally it gave out. I figured fuel pump, so I ended up with a running donor car in the form of a FL 4.2 A. I changed fuel pump (the old one was turning when I put 12v direct but thought I'd take no chances), the relevant relays and fuel pressure regulator.

I filled tank to 3/4 and it ran sweet.... for 10 minutes.

Is there a situation where the housing gets primed by fuel coming down the filler pipe then runs out? And if so, what is the fix? Things I'm missing?

Any suggestions appreciated before I delve back into the fumey boot